Elementary Rules of Usage
1. Form the possessive singular of nouns by adding        's.
Follow this rule whatever the final consonant. Thus write,
    Charles's friend
    Burns's poems
    the witch's malice
Exceptions are the possessives of ancient proper names ending in -es and -is, the
possessive Jesus', and such forms as for conscience' sake, for righteousness' sake. But
such forms as Moses' Laws, Isis' temple are commonly replaced by
    the laws of Moses
    the temple of Isis
The pronomi ...